Method and means for measuring center distances



April 13, 1965 o. E. soRENsEN 3,177,588

METHOD AND MEANS FOR MEASURING CENTER DISTANCES Filed Dec. 5, 1962 5 Sheets-Sheet 1 INVENTOR. t'to 501mm ATTORNEY April 13, 1965 0. E. soRENsEN 3,177,588

METHOD AND MANS FOR MEASURING CENTER DISTANCES Filed Deo. 5, 1962 5 Sheets-Sheet 2 IN V EN TOR.

g. 2] (9i/Ito Sake/nden ATTORNEY April 13, 1965 o. E. SORENSEN 3,177,588

METHOD AND MEANS FOR MEASURING CENTER DISTANCES Filed Dec. 5, 1962 5 Sheets-Sheet 3 April 13, 1965 o. E. soRENsl-:N 3,177,588

METHOD AND MEANS FOR MEASURING CENTER DIsTANcEs Filed Dec. 5, 1962 5 Sheets-Sheet 4 A TTOHNEY April 13, 196s o. ESRENSEN 3,177,588

METHOD AND MEANS FOR MEASURING CENTER DISTANCES INVENTOR.

33 (9b/bd Soie/ruim BY f7 f Patented Apr. 13, 1965 United States Patent Oiice Calipering instruments =have been proposed for measuring and indicating by direct reading, i.e. without mental computation, the distances between physically unmarked Or indiscemible centers of two circular spaced apart holes `or other empty spaces that are bordered by caliperable boundaries. The most practical of such instruments have been of the dimension averaging, beam calipers type in which a scale beam carries graduations progressing from a zerof or starting graduation that are marked by indicia denoting half-values of the true distan of each of such indicia from the Zero or starting graduation. In such instruments, and in contrast to conventional beam calipers, the actual spacings of the graduations is double that of the dimensions denoted by the scale indicia.

In the use of such prior instruments a first calipering step has' been to separate two calipering legs a distance apart equal to the distance that separates the holes. This has been followed by a second calipering step involving a further or additive separation of the calipering legs along the same scale a distance composed of a repetition of the said distance of hole separation plus the sum of the diameters of the holes. One half of the total extent of leg separation thus set oil sequentially and additively along fthe Isame scale will indicate on a half-value denominated scale the true distance between the uncaliperable centers of ythe holes. A dimension averaging instrument must have its scale of graduations calibrated with half-value indicia in order to be able to read directly on the scale the true distance between the hole centers. As `an example,

`in orderto measure and indicate a distance between hole centers which actually, say, is twelve inches, a scale of graduations has been necessary which actually is more than twice as long as twelve inches while the scale indicia need read only up to the said twelve inches. This obviously requires that the overall length of the instrument be much longer than a conventional beam calipers and results in the instrument becoming unwieldy when center distances of substantial length are to be measured or tested. To maintain rigidity in a beam of such excess length, the beam must have a width and thickness that is undesirably heavy to handle. Also the cost of manufacturing beam calipers with a scale of graduations having distortl ed or artificial measurement indicia is increasedbecause of departure from conventional practicesin manufacture. An instrument, thus artificially graduated, is impractical of'nse in ordinary measuring or testing of workpiece dimensions and therefore requires that a shop, to be prepared for etiicient measuring of center distances, must purchase yand keep in stock both a regular and a special kind of beam calipers.

Heretofore,fin vattempts to avoid the above disadvantages and tov be able to ascertain center distance by direct reading of conventional indicia, i.e. indicia which denote true measurement values of the spacing of the graduations, it has been proposed to mark such scale, not on the main beam of the instrument, but on some auxiliary rod or bar that is slidable with respect to the main beam into positions projecting endwise therefrom. But this likewise requires'the same undesirable excess of overall length of the instrument in proportion to the linear extent of the work that is to be measured.

An object of the present invention is to combine in a beam calipers capable of giving a direct reading of non caliperable center distance the advantages of an instrument of minimum length having scale graduations denoted by conventional indicia so that a single suchV instrument c'an be used for both ordinary measuring of distances between caliperable points as well as for measuring and giving a direct reading of distances between uncaliperable or imperceptible space centers.

A related object is to avoid repetitive calipering of the distance separating the holes in the movement ofcalipering legs along the scale so that such distance does not require to be halved but only the sum of the diameters of the holes needs be halved in the functioning of the instrument` This is done according to the present improvements by establishing on the scale a marker slide associated with movement halving mechanism which provides a means for automatically reducing by one-half the extent of backward travel of the marker slide toward' zero when the calipering of the nearest sides of two holes follows the calipering of the farthest apart sides of said holes. In effect this reduces the calipered measurement of only the sum of the diameters of two holes to a measurement that is the sum of the radii of the holes whereby the distance of separation of the holes needs ynot be halved because it never became doubled in the calipering operations.

My improved method contemplates either of two nal method steps for arriving at a'correct reading of center distance on a truly denominated scale of measurement indicating graduations. One of such final steps is to set olf additively on the scale from the graduation correctly indicating the distance separating the work holes a distance equal to the aforesaid sum of the radii of the work holes. Au alternative final step is to set off subtractively on the scale from the graduation indicating the distance between the farthest apart borders of the work holes this same sum of the radii of the work holes.

Instructions for practising the improved method and constructing an instrument embodying the invention that may be used as an aid in performing such method are contained in the following description having reference to the appended drawings wherein:

FIG. 1 is an elevational view in larger than actual size showing a successful form of improved beam calipers incorporating the invention for ascertaining center distance in accordance with my improved method.

FIG. 2 is a plan view looking at FIG. l from above.

FIGS. 3, 4, and 5k are views taken in section respectively on the planes 3-3, 4-4, and 5 5, in FIG. 1, looking in the direction of the arrows.

FIG. 6 shows a modification of parts of the instrument of FIGS. 1 to 5, inclusive.

' FIG. 7 is a view taken in section on the plane 7 7 in FIG. 6 looking in the direction of the arrows.

FIG. 8 is a partially dimensioned diagram illustrating a problem in center distance measuring typical of the need for the present improvement in beam calipers.

FIG. 9 diagrammatically represents a beam calipers mostly like that of FIGS. 1 to 5, inclusive, except equipped with pointed calipering legs as relatively positioned for storage or when not in use.

FIG. 10 shows certain slides of the instrument of FIG. 9 carrying pointed legs that have been separated to an extent equal to the distance between the farthest apart boundaries o-f the two circular areas in FIG. 8 whose indiscernible center distance is to be ascertained.

FIG. 11 shows a second step in the measuring of said center distance whereby the movable slide-carried calipering leg has been returned toward the other calipering leg to an extent to reduce the space therebetween so that said space accords with the distance between the nearest together boundaries of the circular areas of FIG. 8.

FIG. 12 shows the same slide carried leg finally separated from the other calipering leg to a differing extent that lies between the extents V'of legseparation in`FIG.1O i

ing on the scale of the Vbeam to 12, inclusive. 1

FIGS. 14,"l5,f 16 and `17V :correspondl respectively to`V FIGS. 9-to l2, inclusive,V and demonstrate successive stepsV` all slides and set screws-and is best illustrated with respect tos'lde 43'inFIG. 1.a i y y For specic purposes of the. presentinvention thereis provided a marker slide 34V movable along beam 12 in the manner of calipering slide 17 v-toyand from abutting relation tothe latterr on the, opposite side thereof from 'calipering leg 1.20.,.Suchabuttlngfrelation is shown inl FIGS. 1, 9, l0, 12,114.115Nand 17. Marker slide 34 can in the measuringzof centerdistanceby making use of the instrumentgconstructed as in FIGS.V l. to Vf7, inclusive',`

when applied to two circular, holes in a work piece. Y K

FIG. 18gshows in elevationV a dilerent modification Y which settings it canbe stayed by'turning down .the

ofthe construction ofi the instrument of FIGS. 1 to h6j '.FIG. ,19"is, a `plan, viewof ythe instrumentof FIG. 18. FIG.20"is la front elevation of the motionmalvin'g y inclusive,*also Aincorporating the present improvements.'

mechanism as viewed fromV the plane 205-120 .in FIGQIQP with vcasing partially broken` away'to'kexposre ,internal4 parts! -V FIG. 21 isya view vlikeFIG; 2V showing parts of lthe mechanism'dilerentlypositioned] ff ,j

FIG. 22 isfa view taken in section on the planes 22v-22j in FIG. 19, lookingintheydirection of the arrows'.

e FIG. 23' isa viewY taken Vin section on Vthe planes,A

23-23in FIG. V19,.looki'nginthe direction'ofthe arrows.

. section on the plane 424-7--24'in FIG.19. looking inthe y direction .ofthe arrows.

FIG. 25 is a view taken 25-25 in'FIG. 24, looking in the direction of the arrows.V

FIGS. 26 to 33, inclusivecorrespond to FIGS. 8 to l2,

inclusive, and demonstrate successive steps in the measurf ing of center distance byi use of an instrument constructed as in FIGS. 18 to 25, inclusive.

FIG. 34 showsa modification of the starting positions of parts of the instrument as distinguished from FIG.y 27

FIGS. l

ner for use in .measuringA center YdistancesV byjme'thods that accord Ywith the invention. f f' -f Thebeam 12 of he instrumentis rigid and Icarries aY scale of graduations r13lfrdenominatedby indicia 14 'as Y true dimensional valuesA of the spacing thereof fromv'a In FIG. l such starting starting Y point 15 Y on the scale.

point is dencnninated.as,the` graduation 'reading0.25,`

with which graduation the index "16l carried 'oncalipen ing slide 17 .is in register when the nearest'togethersensing edges 18 and 19 of calipering'legs 20 and'21, respec-y tively, are closed Yinto mutual abutment.V To avoid strain ze Y s .housin'g48 open at bothends andmounted xedly `by I.in ,section on they plane when calipering legs are used Vlike those inFIGVS. 1Y tov -be stayed against shiftingalong y v Y by means of-.a thumb screw 35. The abutting of slides 22'and'34 takes vplace at arstop lug' Y the beam f or released for sliding therealong 36 on the former and alug 37V on the latter.-l

f f In addition'to slides 22" and 34 there is needed inthepractice of this'improved method an anchorage device 4which-is here shown v'as a third slide .43 V'freely' movable along the.V scale beamA 12 to various settings in any of o thumb screwV 44 inthe manner voffthumb screws 26 and 35.

SlidesZZ, 34-andj43Y are intercymnectedY by a mech- 'Y anism thaty causes-marker slidel34 to trail the calipering slide 22 along beam 12 inthe direction toward calipering legrr20fwithV anextent of travelV 'that Yis always vhalt the ,extent of travel of thefcaliperingf slide in said direction.

' Such mechanism'may'take various forms but in FIGS. 1

'y 'screw' 47 on `a boss449 y a 34. The vhollow .ofhousing l48yis spanned by `a pivot Y to 6 vis shownto comprise a l.hollow voatin'g frame or n the rear iaceY of marker slide lpinY vjnremovably.lodged-in theV top and bottom walls 3G FIG. 24'is ah'eenlarged fragmentaryview takenk thereof. .y A compound: or doub1y.-grooved pulley 51 turns freelyv on pin 50 within :rigid thrustvba'.rs; 56rand Y57 areslidable relatively to each Y rto @6 yshow inenlar'ged 'size-aportion of thef whole length of labeam calipersconstructe'd in a man- 1 on the calipering legsfrom accidental impactA therebeA Y slide 17V in FIG. l abuts tween, the AVleft edge of the box oibody'portionV 22 of j rmly against f the right 'edge of a strop shoulder 23 .that-is rigid with leg 20.*r Stop shoulder 23 maybe'v a permanent and fixed lug on beamV i 12 or may comprisey the right edge of-a slide member 24 that is movableal'ong thescale beam-.but is` brought to rest in itstr'avel toward thefleft lin FIG.r 1 by a head f 25 fixed on or integraly with the beam :12. YFor purposes of the :present improvement parts 12,Y 20, `24V anda25 rm'ayn all vbe regarded as either fixedlyunit'ed or integral.Y I

"other" and relatively yto Y Y bars VVis tiedA to the'other by.y taut unstretchablev flexible var1dj59v entrainedrespectively about ,lmetallio ribbons-58 l a Y the grooyeslinwspool 51A and anchored vat each end to ai" housing 48. x Eachj `of these `thrust differentl one ofthe Vthrust barswhich vthey serve to connect. end ofithrust bar V5 6 that Iis external tothe Vleeft, endofhousing 48 yis'iixedly but removably secured byv bolt to a lug V6? projecting with -calipering slide '22, while Y thatisV external to thefrightfend.y of housing 48 is but removably seeured'to a rlug'61projectingrearward jtrom and rigidwith anchorage slide 43. v l, Y

rearward Vfrom. and rigid an endv of thrustlbar 457 xedly In themodifiedconstruction of F IGS.` A6v and` 7, the parts kare as y.shown inFIGS. l. and l6 Aexcept vthat a spur pinion 'f 68, that kis freely rotatable'- on pivotv pin 50 is substituted lforspoolSl, and for the steel V.ribbons 58and 59 there arersubs'tituted racks Vof gear yteeth` 69V and 70 on thrust barsV 56 and 57', respectively.`

In use ofymy improved instrument asnext to `be described, will be understood? from FIG. 2 that each increment ofslidingmovement Yof; eitherl the kthrust bar 56 Vor'thge thrust bar k57 relativejtohousing 48 is "accompanied vautom'aticallyV by an 'exactly-y equal incrementlof movev mentfof the other fof said-bars ,inthe opposite'direction 'relative toV thefhousing 48.'- The 4same, is trueof, thrust barsf56and57 in'FIG; 6. And-it willbekpt in mind that the housing 48 is in oating relation to beam 512 since ments of vrriarker slide'34, f

dit shifts positiontherealongtinunison with the 'movek1 Operation of? the instrumentdn carrying out the pre-v sently` Vimprovedmetilods .of; center .distance measuring Aandtesting-will be described vwith'reference to diagrammaticgFIGS; 8 .toV 12, wherein the calipering legs -are V`Vpointed instead of? having substantial width as in VFIGS.

lato 7 and 13 `to17. f.

Calipering slidewll-canbe fastened Vor. released at any position along'the beam'by means of the'thumb `'screw 26 which, ais-iniconventional practice,'actsfas arset screw against 4a 'leaf spring 27 that lbears between thevto'p edge Y ofthe beam in a groove -in fthe Yboxportion V22 4'of the f -slide and affords vfriction lightly` opposingl shiftingv of the slide along the beam when thumb screwf26 is eased outward. This type ofconstr'uction'v can rbe repeatedrwith In FIG.9v slides A17 and34' ,theiinstrument are pushed V'totheextrerne left andV index )16]on calipering slidef17' vregisters with a starting pointonthe scalewhich is coincident with vtheVV scale graduation denominated ,0-` This correctlyindica'tes'on the scale the extent of separation of the worksensing points' which-"to all' practical purposes is zero.f."For calipering Ythe farthestapart -boundaries of the.

twocircularspace areas in 8, 'with all thumb'scr'ews the housing. YTwo push-pull 26, 35, and 44 loosened, calipering slide 17 is shifted fromits position in FIG. 9 to its position in FIG. l0 while the marker slide 34 and anchorage device 43 move in unison therewith. The separation of the leg points then becomes 21/2 and is so indicated by the index 16 on the beam scale. Such separation is the sum of the diameters of the circular space areas 11/2 plus such distance 1" (if any) that separates said areas.

From this calipered 21/2 the step next is to substract mechanically the sum of the diameters of the two space areas which is 11/2, leaving the separation of the calipering leg points reduced to the distance 1 that separates the'space areas as shown in FIG. 1l which is done by shifting calipering slide to the left from its position in FIG. 10 to place the leg points in calipering register with the nearest together sides of the circles in FIG. 8. In such shifting of the calipering slide 17, the anchoragedevice 43 is xed on beam 12 by tightening screw 44 and the mechanism comprising parts 48, 51, and 56 to 59, inclusive, causes marker slide 34 to trail the calipering slide 17 toward the' left from its broken line position to its full line position in FIG. 11. Here the marker slide will now be fastened' in fixed relation to the beam by tightening thumb screw 35. This trailing movement of marker slide 34 will have equalled exactly one-half the extent of movement of calipering slide 17 from its position in FIG. 10 to its position in FIG. 11.

Now with marker slide 34 thus lixed to the beam and both calipering slide 17 and anchorage device 43 free t0 travel along the beam, thumb screw 44 having been loosened to so permit, the calipering slide can be shifted toward the right from its position in FIG. 11 to its ultimate position in FIG. l2 where it is restored into abutting contact with the marker slide 34. Simultaneously, since the position of housing 48 along the beam is now temporarily lixed, the anchorage device 43 will idly be drawn to the left to its position in FIG. l2.V Thus the distance that calipering slide 17 moved from its position in-FIG. 10 to its position in FIG. ll has been halved and this translates a calipering of the sum of the diameters of the space areas into a scale reading of the sum of the radii of the space areas, leaving. incorporated in the reading of measurement on the scale that actual distance (if any) .Which separates the space areasvwhose center'distance is to be ascertained. The resultant reading on the beam scale is 1% the correct dimension of the center distance.

While the use of our improved beam calipers has been described as a series of steps in manipulating the parts thereof, such steps do not require'the use of the slides 22, 34 and 43v on the beam 12 as a mere method of ascertaining center distance accordingto these improvements and without computation. For instance the method may be employed byusing only the graduated beam 12 in conjunction with an ordinary pair of draftsmans or machinists dividers in the following manner. First, and referring to FIG. 8, the dividers would be set to the dimension 2.5 and that distance laid oli'` from the zero graduation toward the right on thescale whereupon the other point of the dividers will fall on the 2.5 location in the scale. This location may then be temporarily marked in any suitable manner without giving attention to the numerical values of neighboring graduations. The dividers may then be set to span the diameter of the largest space circle in FIG. 8 designated as l and then used to set oif this dimension toward the left from the marked 2.5 location on the scale thus to arrive at the 1.5v location which may then be temporarily marked without attention to the numerical value of neighboring graduations. The dividers may then be set to span the diameter of the smaller circular space in FIG. 8 and then used to set oi this distance 0.5 farther toward the left on the ,scale in FIG. l0 whereupon the other point of the dividers will fall upon the 1 location in the scale. The space between the rst marked 2.5 location and the last said 1" location on the scale may then be divided into two equal halves by use of the dividers as is conventional in halving any desired lineardistance. 0r if proportional dividers are used, set in l-to-2 ratio and having two pairs of spreadable points, one point of the farthest spread pairV of points may be placed on the already marked 2.5 location and the other point of said pair placed on the alneady marked 1" location whereupon the distance between the narrower spread points olf the proportional dividers will become exactly one-half the distance between the farthest spread points of the divider. The thus obtained half value of the distance between the 2.5 location and the 1 location thus set up in t-he dividers can then be spaced olf forwardly or to the right from the 1" location, or backwardly to the left from the 2.5 location, whereupon the other point of the dividers will fall on the 1.75" location of the scale just as the index 16 registers with such location in FIG. 12. In this manner the steps of my improved method are seen tofbe capable of being employed without the use of the slides 22, 34, or 43 and the center distance, labeled to be found in FIG. 8, will have .been ascertained without attention to the numerical value of any of the intermediate locations on the scale and without mental computation of any kind as is the object of the invention.

In FIGS. 13 to 17, inclusive, the mechanism 51, 56, 57 and 48, which serves mechanically tointerconnect the slides,-is assumed to `be present as in FIGS. 8 to 12, inclusive. The main purpose of FIGS. 13 to 17 is to explain that where the calipering legs of the instru-ment are not pointed, .but have substantial width aggregating say 1/2 when in mutual abutment as indicated in FIG. 14, the placement of the index 16 on the slide 17 shall be such as to register with a starting point 15 which is coincident with the .25" graduation of the scale instead of with the zero graduation of ythe scale. This compensates for one-half the combined widths of the sensing ends of the ycalipering legs 2th and21, namely the distancebetween'the outer sensing surfaces 28 and 29 of the leg ends when their inner' sensing surfaces 26 and 21 abut. Obviously the starting point on the scale should coincide with ,whatever graduation is denominated to be equal A.to yone-half the combinedk width of the legs, or what amounts to the same thing, thev distance between the center lines of the two legs indicated to be Mi in FIG. 14.

In use of the instrument when constructed as in FIGS. 1 and 2 or FIG. 6, it'has been proposed that thebar 56 may be fastened permanently to the lug 60 that projects ixedly from slide 22. This results in the need for all three slides 17, 34 and 43 to be moved in unison along the beam 12 in carrying outkthe step of the method that consists in calipering the larger workpiece dimension, 2.5 inches, as illustrated in FIGS. 9 and l0 and in FIGS. 14 and l5. Should this be found to be an impediment to the `sensitiveness with `which the legs of the instrument can be shifted to match the dimension of the workpiece, a modification of the construction shown in FIGS. l, 2 and 6 is shown in FIGS. 18-25 wherein only the calipering slide alone need be moved for adjusting the legs of ther instrument to an extent of separation that accords exactly with the dimension of 2.5 of the workpiece first to be calipered.

In the modification shown in FIGS. 18 to 25, inclusive, the slides 17, 34 and 43, hereinbefore described, are replaced by slides 74, 75 and 76, respectively. The beam 12 and itsgraduations may remain the same, but for purposes that will later. appear the calipering leg 80, otherwise like Ztl', is not integrated with nor permanently fixed on beam 12 but is carried by a box 81 that is adjustable lengthwise of the beam and can xedly be set in adjusted position thereon by the lock screw 82. Also for purposes hereinafter explained the calipering leg and the companion leg 83, analagous to leg 21, are re-. movable from the box 81 and from slide 74,V respectively, so as to be replaced by legs of differing kinds such as shown in FIG. 34.

y of anabutting `head 86 Vot ythe -four v pivot pins tually a vsmall gaplilt),

' Again referring'to v'gap 100 therein.

obliquely from bar Y96l ina directionof incline oppositew..

' i ,havinglno/widthatjtheir workl sensing points.

areasfhaving no caliper-able centers are as-l Y es in aV closely fitting aperture in "'.Csliperinggfsiide 74.55 dees nde i'zjcarrie the index which are marked along f substituted v forflegs. mark 16 at the z'ero7 osition of the vernia graduationsthe bottom of vthefwindow4,

graduation on the beamlcarriedl scale..` of'graduations.

Slide 74 also carriesjthe lug85 aki'nto lug v60'inFI( .2, f Y

injecting from' the face 'ofthe box and slidefto permit the but. in the modificationA being described thisjlug 8 5 is no a'pushepull'bar ofthe lmotion FIGS. 2.and 6.]Ins'teadit i on the push-pull bary 8 7jof'the longer fixed permanently to halving mechanism asin merely projects backward fromthe slide into 'the-path modified motion halving mechanism.

Thismechanism. in FlGS.fl 8 to'25,V inclus'ive:.,jcorn?VVV 90v open atv both ends and mounted fixedlyby Vscrew .91 on a boss 92 prisesv a hollow floating Vtrarne or housing projecting from the rear face ofA marker slide 75.4 VThe hollow of housing 90V is spanned 'byY tour .pivot pins alike, lodged inthe `Jiront andrearwalls thereof. Two

pulleyV vwheelsv V94 .alike turn freely on two of the pivot pins within opposite en additional support wheels movement in parallell paths by .continement'between wheels 94,95 andj guide rollers to turn on" a pivot Astud 19 8 tween thebars 87, 96 and the'wheels' able belt-99 of thinY andpreferably highlyftempered steel,

' such as watch spring stock, is' tightly entrainedabout tangentially o'n support wheels 's endless .butf as Va :means ofv keeping ittaut about pulley wheels 94,' 95thereis aci, betweenv theends thereof v"(se'ej FIG. 24)'V which ends arelkept constantly `drawn toward pulley `wheels 94 and' rides 95. Operatively belt ..99

each othertby'thefollowing belt tightening device..

from vbar 96 through an'aperture 104 that f-vspur pin'105 andv engageseanaperture 107 'inbelt'f Tensioning p inj106l is iiixedly carried vin a plunger l108that is slida ble` leng thv d portions of housing v90. Two

v95 turn freely on'lthe .other two 93. `iAnother" push-pull rigid 'bar 96, comparable .tobar 57, is slidable Vrelatively to kbar 87 and tohousing 90. f j Bars 87 and 96. are confined .to longitudinal sliding Y c alipering slide174 can Vbeam*scale that registers` 1 accords with half the overall'width of the Vsensing ends Yof' both calipering legs r'conibirr'edf Then-both calipering Vlegs can beestablished in stafrting position by'shifting r80',":'8 3"in ..18j` th'e- Iegs are removably lodged on thebfox 81'v and slide 74,' respectively,

by" means of two holes in'each legthatregiste'r with'and iitsn'ugly on twodowel pins .'126 projectingfrorn the .boxV

and fro'm the slide and which have enough .sprin'g in aV lateral directionY away from retainer studs 127 also pro.-

shank of eachflgto .bepressed o ntoV the Vdowel pinsand snap into. retained pos'itionun'der v the heads of Astuds127 to be'y very slightlyoverhung therebyor studsfrlz'l 'may be screws. that thread into .box 81 or slide 74 and thus box 81;to different' fixed positions along' the end portion of beamlzyaccommodates and interchange of calipering leg'sof-'difierent style" because the index mark 16'on the b 'e set inA a` starting position on the with' a scale graduation that box4 81 'toward calipering slide 74jalong the'beam until abutment takes place to establishand maintain-acorrect vstarting positionfor the slide74 inf successive usesof index ma withgraduation .025" onthe beam-scale instead of -with Y O graihiat-ion"fon FIGS..24` and 2 5,.the Il JeltQtightfener comprises a spe; pin 1105 tight in andprojecting .QbliqnelyL in belt v`99i nearf.tl1e' l.

Avv tensioning VV.pin l1 06 falso-'projects I holes. orfother wise of bar 96 yWithin aborje 109therein andprojects'- laterally.V from plunger 108 communicating with boreV up by-acomp'ression1spring1111the anchored end of belt 99toward eachy othersoas tomaintain ,thegap 100 vatV a minimos.V thus keeping the-belt reliably tight about thepulleywheels 94, 94.', Y

From F1os j 2 1- and' r24 it win isa 'be crear instruit-f ningof thebelt 99willicause'bar 9610A movejinunison'fv ltherewithgin V either direction .of its lengthwise. movements. B ar v87 is likewise caused toyrnovein unison with equaljdi'staneesfinrespectively'opposite directions.;Y v.

' r`I prefer tofmount'pulley wheels 94 .on roller o r needle bearin'gs71 because Wheels 94 turn'whileunder the load l imposed bythe rtensioninglof belt'99. Also..the. support 'wheels 95.:have a circumferential/groove -to permit the 'reepaSSin'gLothe tensioning .pin 106 and the. sp'uppinsff'. `i105, .1 161and 117.V Housing 90 isjequippe'd with astop of movement ofbar head 86 in .1-20Lto limit. fthe extent warditoward the housing. l 'f f Inforde'rfthat' ca liper'ing legs :124,"12s'1ike' these hewn in P IG. 34,' 'or legs orany otherV desired. style,' maybe throughan elongate slot 110 Y 1109.V Plonger, 108 is backed by jthe;.adjustabii ity half the 'overal-l width of. the'calipering Ylegsis ;025."`and that lei-16 onthe cal-ipeing slide therefore registers explained whelllfqupped with pointed legs'theoretically The circles,

zsxeeeihe-'sameasin FrGs. s and 1s. FIGS; 26 toS35-inclusive,l show YVonepossible series of steps that can beperformed by. theinstrurnent of FIGS. 18425; in carrying out thepresently limproved method Yof centerdistanice measuring.v

Frosfs arregla .condition oftheinstrument when picked up yfor 'use maybe as 'in;=FIG. 27jlwhere1the pointed'calipering v'villjbe apparent that spur pinY 105 and tensioning pin-g106fconstantlydraw the endsl of..

A typical. wayV ofus' A-g an instrument haV-ingthe modiriied construction of FIGS.1`825 in measuring the center distancefof two'holes separated and'dirnensioned as in and repeated in PTIGQ 26, islas follows:

.legs 80,183 abut without spacetherebetween 'and the iride?, mark. 169i alirrins. s1ide.7.4.fegisters With'the zero graduationon scalebeam '12." Si n'ce"the head .86

of. bar-87is nowfree toseparate fromthe lug 85oncalipering slide '74, the latter vmay be A.left unmoved and the marker Slide 75.togetl1'r withanchorage slide. 76V moved f far to the right .on .beam 12'.. into `any` arbitrary Yout vof th'ewaygposition illustrated byJFIG.

"L vThis'leaves ealipering` lide '74 ltreeato'fbemoved alone Y to the right forseparating legs 80,- 83 tothe lengthiest of thecalipered distances, 52.57. -asshown in- FIG.. 29..' In

this'positionthe ealipering slideg74 .will beftemporarily locked tothe-beam 12fby means of its set screw.

. -While-calipering slide V74` i 'r ema 1in s thus `locked in its positionrnarkerslide. .and anchorage slidef76 in unison Wil1' .-be ainovedto the vleft untilfthe .former slidelabuts against: the now locked 'caliperingslide atAv which timethe head 86 of har -.87"willyhave=resumed contact 'with the lugY 'on Ythecaliperin-g slide. The anchorage slide 76 theslide 74 or thescale' beamlZ toaccompany a change 9 will now be locked by means of its set screw on beam 12 in the position shown in FIG. 30.

' In FIG. 3l the calipering slide has been unlocked from the beam and moved to the left, again free from the head r86 of bar 87, until the legs 80, 83 are brought into calipering register with the distance 1.0 separating the .holes that are bein-g measured. Calipering slide 74 is again vtemporarily locked in place in this position in FIG. `31.

Recalling that the anchorage slide 76 remains locked to the beam and that the calipering slide 74 is also again 'now locked to the beam, the marker slide 75 is moved to the lett until the head 86 of bar 87 touches the lug 85 on the calipering slide 74. When this occurs the; marker slide will have moved to the left exactly half the distance that calipering slide 74 was moved to the left in FIG. 3 in reducing the greater calipered distance of leg separation 2.5 Yto the less calipered distance 1.0". In other words the marker slide will have been moved to the left 0.75 which is the sum of the radii of the work holes instead of the sum of the diameters of the work holes. Also at this stage of the operation it will be noted that the distance'of separation of the work holes has not been set otfl twice additively along the scale as it has been explained must be done in the use of a dimension averaging instrument cfor measuring center distance.

All that now remains to be done is to lock marker slide 75 to the beam in its position shown in FIG. 32 and to unlock both calipering slide 74 and lanchorage slide 76 from the beam, after which the simple return movement of calipering slide 74 to the Iright yuntil it again abuts against the now locked marker slide 75 adds to the 1.0 separation oflegs Sil-83, .which is 'the distance between the holes, the distance of 0.75 which is the sum. of the radii of ythe holes. The exact true center distance 1.75 is now accurately indicated by index mark 16 against the true graduation 1.75" on the scale. All calipering. movementjof slide 74 has been free and unencumbered by having to move with `it either the marker slide 75 or the anchorage slide 76.

It will be apparent that as a means for automatically halving the extent of slide movement at any stage in a center distance measuring operation the movement halving mechanism of FIGS. 18-25 can readily be substituted for the movement halving mechanism of FIGS. 2 or 6 by merely securing the bar 87 to the lug 60 instead of leaving it `free to separate therefrom. Likewise the movement halving mechanisms of either FIG. 2 or FIG. 6 can be substituted for the mechanism of FIGS. 18-25 by freeing the bars 56 or 56' from fixed attachment to the lug that is carried by the calipering slide. These and other variationsof the shapes and arrangements of parts herein disclosed can be resorted to as a means of practicing the present improvements and all such variations which come fairly within the scope of the invention as delined by the appended claims are intended to be covered thereby.

yI claim:

1. A beam calipers -for ascertaining without computation ra distance between indiscernible centers of a pair of separate spaces by calipering boundaries of the respective spaces comprising, a beam carrying a scale of graduations denominated as true dimensional values of 4the spacing thereof from a starting point on the scale, first and second calipering legs extending laterally from said beam, a calipering slide movable along said beam carrying said second calipering leg and carrying index means positioned to register with said scale of graduations, a marker slide movable along said beam to and from abutting relation to said calipering slide at the opposite side thereof from said first calipering leg and releasably xable in position on said beam, :an anchorage device releasably fixable in position on said beam at the opposite side of said marker slide `from said calipering slide, and automatic motion proportioning mechanism so interconnecting said 10 anchorage device and said marker slide yas to cause said marker slide to move along said beam simultaneously wit-l1 movement of said calipering slide in the same direction along said beam with an extent of travel equal to half the extent of travel of said calipering slide when said anchorage device is fixed on the beam.

2. A beam calipers as defined in claim 1, in which the said automatic motion proportioning mechanism includes members operatively related respectively to said calipering slide and to said anchorage device, and means in fixed relation to said marker slide operatively interconnecting said members in a manner .to insure equal extents of movement thereof relative to said marker simultaneously in respectively opposite directions.

3. A beam calipers as defined in claim 2, in which the said means comprises a frame including an elongate housing fixed on the said marker slide flanking the face of the beam opposite the said scale of graduations and out of whose opposite ends the said members respectively project.

4. A beam calipers as defined in claim 3, in which the said members are parallel and rigid and overhang each other lengthwise of the said beam.

5. A beam calipers as defined in claim 4, in which the said rigid members are operatively interconnected by at least one flexible ribbon.

6. A beam calipers as defined in claim 5, together with pulley means having said flexible ribbon entrained thereabout.

7. A beam calipers as dened in claim 6, in which the said pulley means is pivotably supported on the said frame.

8. A beam calipers as defined in claim 4, in which each of the said rigid members carries a rack of gear teeth, together with a gear pivotally supported by said frame in mesh simultaneously with both of said racks.

9. A beam calipers as delined in claim l, in which each of the said slides and the said anchorage device carry independently manipulatable set screws cooperative with the said beam selectively to fasten or release said slides or device individually against movement along said beam.

lO. A beam calipers as defined in claim 1, in which the said automatic motion proportioning mechanism includes two rigid parallel members operatively related respectively to said calipering slide and to said anchorage device, a frame iianking the said beam carried by said marker slide, pulley wheels pivotally supported by said frame, and a belt trained about said pulley wheels having two stretches extending therebetween to travel simultaneously in respectively opposite directions, said two stretches of belt being fastened respectively to said two members, whereby movement of either member relative to said frame causes equal movement of the other of said two members in an opposite direction relative to said frame.

ll. A beam calipers as defined in claim 10, in which one of the said members is fastened to the said anchorage device and the other of said members is in abutting relation to and separable from the said calipering slide.

l2. A beam calipers as defined in claim l0, in` which the said belt intervenes between the said two members and the said pulley wheels.

13. A beam calipers as defined in claim 12, together with a straight row of guide means on the same frame contactable by the faces of the said members opposite the said stretches of belt.

14. A beam calipers as dened in claim l2, together with guide wheels rotatably carried by the said frame between the said two stretches of belt and between the said two pulley wheels located and of size to be contacted by and contribute to the support of said stretches of belt.

l5. A beam calipers as defined in claim l0, in which the said belt has a gap in one of its said stretches bridged by one of the said members and separating end portions of the belt, one of said end portions of said belt being fixed to one of said members, and automatically acting in accord with the distance fence by said second extent of spread; dividing `the distance t '16, Arbeamcalipers as denied; in claim 15, in wiiihV Y the said automatically acting Vbelt tightening means' in.

cludes a catch engageable with the said otherend portion of the said belt carried by the said one of thessaidrnernf bersv in a manner to shiftrelatively thereto in the VVdirections of travel rof Said belt, Yandv a1/Spring biasing Said.

catch .to so shift relatively to said member in AAa direction tending yte elese the Said` een between. Seid'end pertiens ofthegbelth" Y Y 17. A beam. calipers as defined in claim 1 6,"in `which agonally fromA thev said one of said members toward the.

said gap. andrhooked into an aperture inthe saidbelt vspaced from said gap.

i l8.Abea1 nj calipers as denedfin claim l'lyftogethei i with spur :pins'lodgedrin and'projecting in converging between said two roferencqlocations on the scale into halffdistances setting olf one of said halfrdistances forwardlyV from s aid`second reference locationjinfa directiony awayl frornfsaidv starting graduation,V and reading on thev truly marked -grannatiens ef Said. Sealeathird leeefien removed from' said'second referencelocation 1 by said half distance, wherebyY theunknown distanebetween said space centersiwill bef'indicatedrby the indicia of theV scale v10 graduation `at said: third location.Vlr

20. The method of Yascertainingwithoutirriental comy," putation the distance: between indiscernible centers ofA a Vthe saidwcatch comprises a tensioning ypin prcecting di#y y Y pair. of .separate spaces by` setting voffV and` .marking ex;

tents ofl distancesy related tor boundaries of said spaces on 15" Y Y t t f dimensionalvalues of the spacing thereof fromastarting( peint ron the escale,r which includestlle steps of,"setting two a scale of graduationsrdenominatedfby'indicia as Ythe true boundarysensmg elements vr"atea firstekte'nt of4 spread in diagonal directions'froml the other ofthe said rigid parallel members and individually hooked into neighboring aper.

tures'respectively in the stretch ofithe` said belt not ren- .Y

gage'd'by rthe -saidbelt tightening means.

19, The method of ascertaining without tation of graduations'denominatedKby'indicia as thetrue di# mensional valuesof the Vspacing thereof from a starting y point on the scale, which includes the ystepsof, /setting-v 3Q .i

Y distance ,between said V'tw two boundary sensing elements:ata'rstl eiitent'of.` spread separatingathe farthest 'apart mentalcomputhe distance between indiscernibley centers of a pair fj of separate spaces vby settingo and markingaextents of distances related to boundaries of said spaces on a yscale boundaries of said spaces, setting olf'said firstVv extentof 4 spread forwardly from afstartingwpoint on'a scale of truly Y denominated graduations and marking .a irst reference10.-Y.l

' cation lonfsaid scalearemovedjfrom said startingpoint by said first extent Vvof spread, setting two elements at a i secondY extent vof spread equal to theosurn of the ward from 4sa'id'irst reference location toward said starting graduation on said scale and?.r marking a second referwidth of said spaces', setting off-saidsecondextent of spread back spread i accord -with the ydistance separating 'the farthest apart boundaries of; said spacesaisettinugoi `saidrfefirstextent of I lfiforwardly from aastarting pzointv'onua scale of truly ydenominated r'graduations and rnarkingaa first reference kloeationon said scale removed ,frornffsaid starting i point by f-,said rst, eiitent spreadysettirig twoele'rnents at asecond extent of` spread equal teo-th 7.sum of the' width of spaces, setting offsaid second: extent` of spread baekwardfrom said kfirst rreference,.location toward said fstarting graduation on said.V scale and marking a second' reference location on saidg vscale .remoyed fromv said first` reference ,byV said second extent of vspread' dividing the reference' .locations on the ettirig; oi ione of vsaid half dis-l scale"intohalf'fdistances; tances jbackwardly from sai "rsti' reference1 location in afdirection toward saidt,startrngggraduation,,and reading on the' :truly marked graduations `of saidgscalefathird location removed-from* saidrst reference. locaticlinv by Vsaidfhalf distance, wh'rebyfth'e' unknown distance between j said-spade centers will ,bindihcated by tiiejillaijia"LofA the,

ence location on said scale'removed from saidflrst refer-l f scale'` graduation at saidl third 1 A cation.v

ffiNorefe'rences cited.'A Q f 

1. A BEAM CALIPERS FOR ASCERTAINING WITHOUT COMPUTATION A DISTANCE BETWEEN INDISCERNIBLE CENTERS OF A PAIR OF SEPARATE SPACES BY A CALIPERING BOUNDARIES OF THE RESPECTIVE SPACES COMPRISING, A BEAM CARRYING A SCALE OF GRADUATIONS DENOMINATED AS TRUE DIMENSIONAL VALUES OF THE SPACING THEREOF FROM A STARTING POINT ON THE SCALE, FIRST AND SECOND CALIPERING LEGS EXTENDING LATERALLY FROM SAID BEAM, A CALIPERING SLIDE MOVABLE ALONG SAID BEAM CARRYING SAID SECOND CALIPERING LEG AND CARRYING INDEX MEANS POSITIONED TO REGISTER WITH SAID SCALE OF GRADUATIONS, A MARKER SLIDE MOVABLE ALONG SAID BEAM TO AND FROM ABUTTING RELATION TO SAID CALIPERING SLIDE AT THE OPPOSITE SIDE THEREOF FROM SAID FIRST CALIPERING LEG AND RELEASABLY FIXABLE IN POSITION ON SAID BEAM, AN ANCHORAGE DEVICE RELEASLY FIXABLE IN POSITION ON SAID BEAM AT THE OPPOSITE SIDE OF SAID MARKER SLIDE FROM SAID CALIPERING SLIDE, AND AUTOMATIC MOTION PROPORTIONING MECHANISM SO INTERCONNECTING SAID ANCHORAGE DEVICE AND SAID MARKER SLIDE AS TO CAUSE SAID MARKER SLIDE TO MOVE ALONG SAID B EAM SIMULTANEOUSLY WITH MOVEMENT OF SAID CALIPERING SLIDE IN THE SAME DIRECTION ALONG SAID BEAM WITH AN EXTENT OF TRAVEL EQUAL TO HALF THE EXTENT OF TRAVEL OF SAID CALIPERING SLIDE WHEN SAID ANCHORAGE DEVICE IS FIXED ON THE BEAM. 